The present invention relates to a head drum base for use in a magnetic tape recording and reproducing apparatus such as a VTR apparatus.
Magnetic tape recording and reproducing apparatus with an automatic tape loading capability generally include a head drum having recording and reproducing heads and a pair of tape loading poles movable along slots in a head drum base between a tape cassette loaded and the head drum. When the tape cassette is inserted into the magnetic recording and reproducing apparatus, the tape loading poles are moved from the tape cassette to positions one on each side of the head drum for drawing a magnetic tape out of the tape cassette and setting the magnetic tape in a prescribed tape path including a partly circular path around the periphery of the head drum. The partly circular tape path around the peripheral surface of the head drum is particularly required to be defined with increased accuracy for better signal recording and reproducing operation with good interchangeability between manufactured apparatus. Therefore, the tape loading poles should be positioned highly accurately with respect to the head drum while the magnetic tape recording and reproducing apparatus is in operation.
Conventional magnetic tape recording and reproducing apparatus have a chassis supporting thereon a head drum base on which a head drum is fixedly placed and a pair of stops for positioning the tape loading poles relative to the head drum. The drum base and the stops are separately fastened to the chassis by means of screws. It has been quite tedious and time-consuming to attach the stops to the chassis with a desired degree of accuracy relative to the head drum. The trend in the actual assembling process is that the stops mounted on the chassis are subjected to varying positional accuracies among many magnetic tape recording and reproducing apparatus.